If you live near a major roadway or other pollution source, you may be more at risk of developing dementia, according to a study published in the May 2015 issue of the journal Stroke. The study found that middle-aged and older people who were exposed to high levels of air pollution had smaller brain volumes and were at a higher risk of silent stroke than those who were less exposed.
Led by scientists from the Boston University School of Medicine and Beth Israel Deaconess Medical Center, the researchers looked at data from more than 900 people who had participated in the Framingham Heart Study. After determining how far the participants lived from major roadways, they used satellite imagery to determine their levels of exposure to air pollution. They focused particularly on PM2.5 particles, which previous studies have implicated in many of the health problems associated with air pollution, including heart attack and stroke.
They found that participants who were exposed to more PM2.5 due to living near major roadways were more likely to experience covert brain infarcts, a form of "silent stroke." These happen without the person noticing them and can be a sign of more serious strokes to come. Even patients who didn't suffer from these silent strokes experienced more brain shrinkage over the course of the study if they lived in polluted areas.
"This is one of the first studies to look at the relationship between ambient air pollution and brain structure. Our findings suggest that air pollution is associated with insidious effects on structural brain aging, even in dementia- and stroke-free individuals," said Elissa Walker of Beth Israel's Cardiovascular Epidemiology Research Unit.